Integrated circuit cards have become popular as a means of conveniently adding memory capacity to personal computers, particularly palm top, lap top, and notebook-size computers, as well as other devices such as modems, serial ports, cellular phone links, facsimile machines, application read-only memories, and the like. To promote compatibility among memory cards, physical, interface and software standards have been adopted by the Personal Computer Memory Card International Association (PCMCIA or PC-CARD) in the United States and by the Japan Electronics Industry Development Association (JEIDA). The PC-CARD Standard Release 2.01, published November, 1992, provides for three physical sizes, designated Type I, Type II and Type III, which are distinguished from each other primarily by specifying card thicknesses of 3.3, 5.0 and 10.5 millimeters maximum respectively. The memory cards are provided with a 68 pin socket connector at one end and are typically guided into place by a pair of channel guides which engage the side edges of the card.
With the Type III card thickness of 10.5 mm maximum specified above, a disk drive configured as a PC-CARD using three disks, as opposed to two as used in the past, would permit a substantially larger memory capacity to be added to the host computer. Heretofore, such a three disk approach within the constraints of the PCMCIA Type III dimension has proven difficult because of the numerous physical packaging constraints which have prohibited incorporating an increased number of heads and disks in the space available.